mineral

Tumbled chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-bearing chalcedony/jasper

AI-generated identification · may be incorrect

Smooth, rounded, translucent-to-opaque brown-gray stone with tiny reddish inclusions and a vitreous-to-waxy luster. Hardness is about 6.5–7 Mohs; quartz has no cleavage and a cryptocrystalline structure.

Identified August 19, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later incorporating iron oxides and other impurities; specimens may range from volcanic-host-rock ages to younger alluvial deposits. Tumbling has produced the polished surface.

Uses & applications

Used for cabochons, beads, carvings, lapidary pieces, and inexpensive collectibles; quality depends on color, pattern, translucency, and finish.

Geological facts

The exact variety cannot be confirmed from one photograph; it could also be a brown agate, jasper, or iron-stained quartz pebble.

Field identification & locations

Field clues include quartz-like hardness, resistance to scratching by steel, and a smooth waxy fracture; it commonly occurs in volcanic regions, gravel beds, and stream deposits. A streak, specific-gravity, or microscopic examination would improve identification.